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      <td><p class="toc level1"><a href="docinfo.html">Document Information</a></p>
<p class="toc level1 tocsp"><a href="gexaf.html">Preface</a></p>
<p class="toc level1 tocsp"><a href="gfirp.html">Part&nbsp;I&nbsp;Introduction</a></p>
<p class="toc level2"><a href="bnaaw.html">1.&nbsp;&nbsp;Overview</a></p>
<p class="toc level2"><a href="gfiud.html">2.&nbsp;&nbsp;Using the Tutorial Examples</a></p>
<p class="toc level1 tocsp"><a href="bnadp.html">Part&nbsp;II&nbsp;The Web Tier</a></p>
<p class="toc level2"><a href="bnadr.html">3.&nbsp;&nbsp;Getting Started with Web Applications</a></p>
<p class="toc level2"><a href="bnafd.html">4.&nbsp;&nbsp;Java Servlet Technology</a></p>
<p class="toc level2"><a href="bnagx.html">5.&nbsp;&nbsp;JavaServer Pages Technology</a></p>
<p class="toc level2"><a href="bnajo.html">6.&nbsp;&nbsp;JavaServer Pages Documents</a></p>
<p class="toc level2"><a href="bnakc.html">7.&nbsp;&nbsp;JavaServer Pages Standard Tag Library</a></p>
<p class="toc level3"><a href="bnakd.html">The Example JSP Pages</a></p>
<p class="toc level3"><a href="bnake.html">Using JSTL</a></p>
<p class="toc level4"><a href="bnake.html#bnakg">Tag Collaboration</a></p>
<p class="toc level3 tocsp"><a href="bnakh.html">Core Tag Library</a></p>
<p class="toc level4"><a href="bnakh.html#bnakj">Variable Support Tags</a></p>
<p class="toc level4"><a href="bnakh.html#bnakk">Flow Control Tags</a></p>
<p class="toc level5"><a href="bnakh.html#bnakl">Conditional Tags</a></p>
<p class="toc level5"><a href="bnakh.html#bnakm">Iterator Tags</a></p>
<p class="toc level4 tocsp"><a href="bnakh.html#bnakn">URL Tags</a></p>
<p class="toc level4"><a href="bnakh.html#bnako">Miscellaneous Tags</a></p>
<p class="toc level3 tocsp"><a href="bnakq.html">XML Tag Library</a></p>
<p class="toc level4"><a href="bnakq.html#bnakt">Core Tags</a></p>
<p class="toc level4"><a href="bnakq.html#bnaku">Flow Control Tags</a></p>
<p class="toc level4"><a href="bnakq.html#bnakv">Transformation Tags</a></p>
<p class="toc level3 tocsp"><a href="bnakw.html">Internationalization Tag Library</a></p>
<p class="toc level4"><a href="bnakw.html#bnaky">Setting the Locale</a></p>
<p class="toc level4"><a href="bnakw.html#bnakz">Messaging Tags</a></p>
<p class="toc level5"><a href="bnakw.html#bnala">The <tt>setBundle</tt> and <tt>bundle</tt> Tags</a></p>
<p class="toc level5"><a href="bnakw.html#bnalb">The <tt>message</tt> Tag</a></p>
<p class="toc level4 tocsp"><a href="bnakw.html#bnalc">Formatting Tags</a></p>
<p class="toc level3 tocsp"><a href="bnald.html">SQL Tag Library</a></p>
<p class="toc level4"><a href="bnald.html#bnalf"><tt>query</tt> Tag Result Interface</a></p>
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<p class="toc level3 tocsp"><a href="">JSTL Functions</a></p>
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<p class="toc level3"><a href="bnali.html">Further Information about JSTL</a></p>
<p class="toc level2 tocsp"><a href="bnalj.html">8.&nbsp;&nbsp;Custom Tags in JSP Pages</a></p>
<p class="toc level2"><a href="bnaon.html">9.&nbsp;&nbsp;Scripting in JSP Pages</a></p>
<p class="toc level2"><a href="bnaph.html">10.&nbsp;&nbsp;JavaServer Faces Technology</a></p>
<p class="toc level2"><a href="bnaqz.html">11.&nbsp;&nbsp;Using JavaServer Faces Technology in JSP Pages</a></p>
<p class="toc level2"><a href="bnatx.html">12.&nbsp;&nbsp;Developing with JavaServer Faces Technology</a></p>
<p class="toc level2"><a href="bnavg.html">13.&nbsp;&nbsp;Creating Custom UI Components</a></p>
<p class="toc level2"><a href="bnawo.html">14.&nbsp;&nbsp;Configuring JavaServer Faces Applications</a></p>
<p class="toc level2"><a href="bnaxu.html">15.&nbsp;&nbsp;Internationalizing and Localizing Web Applications</a></p>
<p class="toc level1 tocsp"><a href="bnayk.html">Part&nbsp;III&nbsp;Web Services</a></p>
<p class="toc level2"><a href="bnayl.html">16.&nbsp;&nbsp;Building Web Services with JAX-WS</a></p>
<p class="toc level2"><a href="bnazf.html">17.&nbsp;&nbsp;Binding between XML Schema and Java Classes</a></p>
<p class="toc level2"><a href="bnbdv.html">18.&nbsp;&nbsp;Streaming API for XML</a></p>
<p class="toc level2"><a href="bnbhf.html">19.&nbsp;&nbsp;SOAP with Attachments API for Java</a></p>
<p class="toc level1 tocsp"><a href="bnblr.html">Part&nbsp;IV&nbsp;Enterprise Beans</a></p>
<p class="toc level2"><a href="bnbls.html">20.&nbsp;&nbsp;Enterprise Beans</a></p>
<p class="toc level2"><a href="bnbnb.html">21.&nbsp;&nbsp;Getting Started with Enterprise Beans</a></p>
<p class="toc level2"><a href="bnboc.html">22.&nbsp;&nbsp;Session Bean Examples</a></p>
<p class="toc level2"><a href="bnbpk.html">23.&nbsp;&nbsp;A Message-Driven Bean Example</a></p>
<p class="toc level1 tocsp"><a href="bnbpy.html">Part&nbsp;V&nbsp;Persistence</a></p>
<p class="toc level2"><a href="bnbpz.html">24.&nbsp;&nbsp;Introduction to the Java Persistence API</a></p>
<p class="toc level2"><a href="bnbrl.html">25.&nbsp;&nbsp;Persistence in the Web Tier</a></p>
<p class="toc level2"><a href="bnbrs.html">26.&nbsp;&nbsp;Persistence in the EJB Tier</a></p>
<p class="toc level2"><a href="bnbtg.html">27.&nbsp;&nbsp;The Java Persistence Query Language</a></p>
<p class="toc level1 tocsp"><a href="bnbwi.html">Part&nbsp;VI&nbsp;Services</a></p>
<p class="toc level2"><a href="bnbwj.html">28.&nbsp;&nbsp;Introduction to Security in the Java EE Platform</a></p>
<p class="toc level2"><a href="bnbyk.html">29.&nbsp;&nbsp;Securing Java EE Applications</a></p>
<p class="toc level2"><a href="bncas.html">30.&nbsp;&nbsp;Securing Web Applications</a></p>
<p class="toc level2"><a href="bncdq.html">31.&nbsp;&nbsp;The Java Message Service API</a></p>
<p class="toc level2"><a href="bncgv.html">32.&nbsp;&nbsp;Java EE Examples Using the JMS API</a></p>
<p class="toc level2"><a href="bncih.html">33.&nbsp;&nbsp;Transactions</a></p>
<p class="toc level2"><a href="bncjh.html">34.&nbsp;&nbsp;Resource Connections</a></p>
<p class="toc level2"><a href="bncjx.html">35.&nbsp;&nbsp;Connector Architecture</a></p>
<p class="toc level1 tocsp"><a href="bnckn.html">Part&nbsp;VII&nbsp;Case Studies</a></p>
<p class="toc level2"><a href="bncko.html">36.&nbsp;&nbsp;The Coffee Break Application</a></p>
<p class="toc level2"><a href="bnclz.html">37.&nbsp;&nbsp;The Duke's Bank Application</a></p>
<p class="toc level1 tocsp"><a href="gexbq.html">Part&nbsp;VIII&nbsp;Appendixes</a></p>
<p class="toc level2"><a href="bncno.html">A.&nbsp;&nbsp;Java Encoding Schemes</a></p>
<p class="toc level2"><a href="bncnq.html">B.&nbsp;&nbsp;Preparation for Java EE Certification Exams</a></p>
<p class="toc level2"><a href="bncnt.html">C.&nbsp;&nbsp;About the Authors</a></p>
<p class="toc level1 tocsp"><a href="idx-1.html">Index</a></p>
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<a name="bnalg"></a><h3>JSTL Functions</h3>
<p><a name="indexterm-500"></a><a href="#bnalh">Table&nbsp;7-8</a> lists the JSTL functions.</p><a name="bnalh"></a><h6>Table&nbsp;7-8 Functions</h6><table><col width="15%"><col width="19%"><col width="48%"><col width="16%"><tr><th align="left" valign="top" scope="column"><p>Area</p></th>
<th align="left" valign="top" scope="column"><p>Function</p></th>
<th align="left" valign="top" scope="column"><p>Tags</p></th>
<th align="left" valign="top" scope="column"><p>Prefix</p></th>
</tr>
<tr><td rowspan="2" align="left" valign="top" scope="row"><p>Functions</p></td>
<td align="left" valign="top" scope="row"><p>Collection length</p></td>
<td align="left" valign="top" scope="row"><p><tt>length</tt></p></td>
<td rowspan="2" align="left" valign="top" scope="row"><p><tt>fn</tt></p></td>
</tr>
<tr><td align="left" valign="top" scope="row"><p>String manipulation</p></td>
<td align="left" valign="top" scope="row"><p><tt>toUpperCase</tt>, <tt>toLowerCase</tt></p><p><tt>substring</tt>, <tt>substringAfter</tt>, <tt>substringBefore</tt></p><p><tt>trim</tt></p><p><tt>replace</tt></p><p><tt>indexOf</tt>, <tt>startsWith</tt>, <tt>endsWith</tt>, <tt>contains</tt>,
<tt>containsIgnoreCase</tt></p><p><tt>split</tt>, <tt>join</tt></p><p><tt>escapeXml</tt></p></td>
</tr>
</table><p><a name="indexterm-501"></a>Although the <tt>java.util.Collection</tt> interface defines a <tt>size</tt> method, it does not conform to the
JavaBeans component design pattern for properties and so cannot be accessed by using
the JSP expression language. The <tt>length</tt> function can be applied to any
collection supported by the <tt>c:forEach</tt> and returns the length of the collection.
When applied to a <tt>String</tt>, it returns the number of characters in
the string.</p><p>For example, the <tt>index.jsp</tt> page of the <tt>hello1</tt> application introduced in <a href="bnadr.html">Chapter&nbsp;3, Getting Started with Web Applications</a>
uses the <tt>fn:length</tt> function and the <tt>c:if</tt> tag to determine whether to include
a response page:</p><pre>&lt;%@ taglib uri="http://java.sun.com/jsp/jstl/core"
     prefix="c" %>
&lt;%@ taglib uri="http://java.sun.com/jsp/jstl/functions"
    prefix="fn" %>
&lt;html>
&lt;head>&lt;title>Hello&lt;/title>&lt;/head>
...
&lt;input type="text" name="username" size="25">
&lt;p>&lt;/p>
&lt;input type="submit" value="Submit">
&lt;input type="reset" value="Reset">
&lt;/form>

&lt;c:if test="${fn:length(param.username) > 0}" >
  &lt;%@include file="response.jsp" %>
&lt;/c:if>
&lt;/body>
&lt;/html></pre><p>The rest of the JSTL functions are concerned with string manipulation:</p>
<ul><li><p><tt>toUpperCase</tt>, <tt>toLowerCase</tt>: Changes the capitalization of a string</p></li>
<li><p><tt>substring</tt>, <tt>substringBefore</tt>, <tt>substringAfter</tt>: Gets a subset of a string</p></li>
<li><p><tt>trim</tt>: Trims white space from a string</p></li>
<li><p><tt>replace</tt>: Replaces characters in a string</p></li>
<li><p><tt>indexOf</tt>, <tt>startsWith</tt>, <tt>endsWith</tt>, <tt>contains</tt>, <tt>containsIgnoreCase</tt>: Checks whether a string contains another string</p></li>
<li><p><tt>split</tt>: Splits a string into an array</p></li>
<li><p><tt>join</tt>: Joins a collection into a string</p></li>
<li><p><tt>escapeXml</tt>: Escapes XML characters in a string</p></li></ul>

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